In a digital-watermark superposing apparatus and a digital-watermark detecting apparatus, a plurality of DCT coefficients for respective frequency components are generated by subjecting video data to a two-dimensional DCT transform for each pixel block consisting of a predetermined number of pixels,...http://www.google.fr/patents/US6111990?utm_source=gb-gplus-shareBrevet US6111990 - Digital-watermark superposing apparatus and digital-watermarker detecting apparatus
Digital-watermark superposing apparatus and digital-watermarker detecting ...
